This invention relates to video display systems and, more particularly, to a method of making a deformable light modulator for use in a video display system. The subject matter of this application is related to the subject matter of my copending U.S. application Ser. No. 574,929, filed of even date herewith and assigned to the same assignee as the present application.
In recent years there have been developed techniques for displaying video information by storing a charge pattern representative of a video frame in a frame store and utilizing the charge pattern to modify a characteristic of a material. The modified characteristic of the material is then used to obtain a viewable image. In my U.S. Pat. No. 3,882,271, there is disclosed an apparatus wherein a charge pattern on a special semiconductor frame store is used to obtain deformations of a deformable material. The deformable material is disposed between an array of electrodes on the surface of the semiconductor device and a thin conductive layer which serves as both a common electrode and a light reflective layer. The deformable material and the thin conductive layer are deformed in response to the charge pattern on the array of electrodes with respect to the conductive layer. An optical subsystem, such as a Schleiren optical system, is then utilized to convert the pattern of deformations (or "ripples") in the thin conductive layer into a viewable image.
An important aspect of the described type of system is the operation of the conductive and reflective layer which is mounted on the deformable layer and must reliably and repeatably provide precise patterns of deformations in the reflective layer which correspond to the charge pattern on the array of electrodes. It has been found that the materials used for the deformable and conductive layers, as well as their dimensions, and their method of assembly, have a profound effect upon operating characteristics, and prior attempts to make solid state light modulators have met with one or more of the following deficiencies: insufficient sensitivity to the applied voltages; inadequate response characteristics as a function of time; and/or instability over the short and long term.
It is an object of the present invention to provide a method of making a deformable solid state light modulator structure which overcomes these problems.